The present disclosure relates to preshrinking and preenlarging of sheets for improved image registration as applied to printing systems. It finds particular application in conjunction with overlay printing and integrated printing modules consisting of several marking engines, each having the same or different printing capabilities, and will be described with particular reference thereto. However, it is to be appreciated that the present disclosure is also amenable to other like applications.
Overlay printing is a printing method whereby a first marking engine prints content on one side of a sheet, and then a second marking engine with different capability prints complimentary content on the same side. In fact, it is possible that monochrome content, CMYK 4-color content, and custom color content could all be desired on the same side of a sheet, such that a given sheet passes through three different marking engines. When consecutively marking a sheet using multiple marking engines, the need to properly register the image content from the different marking engines becomes a factor which affects the overall quality of the printed sheet and ultimately customer satisfaction. The accuracy of registering a sheet for subsequent making can be a function of many systems, including but not limited to sheet control, sheet dimension stability and/or predictability, marking engine control, etc.
This disclosure relates to sheet dimension stability; specifically, the shrinkage or enlargement of a media sheet as it passes through a marking engine. As a sheet is passed through a first marking engine for image marking, the sheet will shrink or enlarge and thereby cause a second marking of the sheet to be misaligned. The third marking of the sheet will also be misaligned as a function of the amount the sheet shrinks or enlarges during the first and second markings. As the sheet passes through subsequent marking engines, additional sheet registration error will occur as a result of the shrinkage or enlargement of the sheet through each marking engine. Depending on the cumulative amount of shrinkage or enlargement, the finished overlay printed sheet can have a noticeable registration misalignment of images and create a lower degree of customer satisfaction with the finished product. This disclosure provides a way to compensate for the cumulative media shrinkage or enlargement discussed heretofore by sending a sheet initially through one or more non-printing cycles before commencing one or marking operations.